Mechanical coupler



FIG. 1 is a top perspective view of a mechanical coupler according to our new design;

FIG. 2 is a bottom perspective view thereof;

FIG. 3 is a front view thereof, the rear view being identical to the front view;

FIG. 4 is a right-side view thereof, the left-side view being identical to the right-side view;

FIG. 5 is a top view thereof; and,

FIG. 6 is a bottom view thereof.

The broken lines illustrate portions of the mechanical coupler that form no part of the claimed design. 

CLAIM The ornamental design for a mechanical coupler, as shown and described. 